NUTS AND VOLTS

Posted in: Developing Perspectives

Just in Time Parts vs. the Junkbox

January 2015 Bryan Bergeron

Cleaning out my workshop reminded me of when I first started my journey in electronics — tubes were still available at RadioShack. My first ham radio transmitter — a HeathKit DX-60B — used a 6146B tube final amplifier (power amplifier), in part because it was inexpensive and readily available. Back then, I had a junkbox with a few dozen tubes, a pound or two of discrete resistors and capacitors, and some miscellaneous hardware. With that, I could repair just about any TV, receiver, or transmitter that I came across or wanted to modify.


Today, things are more complicated, in part because of the vast array of specialized solid-state components and assemblies available. Moreover, the shelf life of these components and assemblies are typically months instead of years or decades.

Don't get me wrong. I look forward to getting my hands on the latest developments in technology. I'm hooked, for example, on the new product announcements featured by SparkFun every Friday, and the broader daily updates on technology from Gizmodo. It's just that it no longer pays to have a sizeable junkbox.

For example, about a year ago, I created a prototype circuit for a government grant application that relied on some high-resolution TFT LCD modules from AdaFruit. However, in the nine months between the grant application and funding, the TFT LCD had been discontinued. As a result, I had to experiment with a new crop of LCDs and newly introduced OLEDs from AdaFruit. I was happy with the new displays, which provided higher resolution, faster response, and no increase in price. However, I had to modify the 3D printer file for the mounting assembly, and rework the software to accommodate the new generation of displays.

Today, after clearing out perhaps 20 lbs of retired ASICs (applicationspecific integrated circuits), breakout boards, and circuit assemblies, my junkbox consists largely of leaded and SMT resistors, capacitors, and a few 3V and 5V power regulator chips. I've downsized from six shelves of "junk" to one shelf of discrete components. 

As a result, there's less to keep track of, and I know where everything is. Previously, it was a hunt to find that elusive chip or breakout board. Now, my hunting is reserved to online searches.

The two to three day time lag is a significant downside, but no greater than working with components that are no longer supported. So far, this “just in time” parts procurement has worked just fine.

As an aside, I've also shifted from what I once considered standard 4-40 stainless nuts and bolts from suppliers such as BoltDepot, to lighter smaller M2x10 hardware from places such as HobbyKing. I wouldn't think of building a drone or any other compact lightweight device with the old hardware. 

However, there's still enough of the heavy duty boards around such as the Arduino UNO microcontroller board to hang on to my supply of 4-40 hardware. I'm sure that eventually — as with my collection of RF vacuum tubes — I'll be tossing these, as well. NV


Posted on 12/14 at 1:01 pm
Posted in: Featured Article

Save Time and Money Making CNC Halloween Decorations

November 2014 Len Shelton Melissa Shelton

When my friend,Vern asked me if I'd write an article for Nuts & Volts demonstrating how to create a Halloween decoration tombstone on a CNC router, I was psyched. I’m always looking for new and interesting ways to show off all you can do with CNC machines. So, I agreed to give it a shot.


Create complex 3D contoured parts by combining fast and simple 2.5D pocketing and profiling operations with manual finishing techniques.

Getting Started

As with any project, you have to do your research. I needed to answer questions like: What do tombstones look like? How are they shaped? What do they say on them? How are people using them in their Halloween displays? Most importantly: How do I make them on a CNC router? So, I got a lot of great design ideas examining epitaphs and tombstones using Google image search. Unfortunately, most of the models I found required 3D contouring. With that type of work, I would first need to spend the time creating a 3D model and even more hours carving it out.

There are three primary phases to a CNC project:

1) Design: The drawing or CAD model.
2) Tooling: Creating the tool paths with CAM software.
3) Machining: Running the tool paths on the machine.

I am admittedly an impatient man. With time being a finite resource we can never get back, isn’t everyone looking for a faster way? So, let me show you how you can use CNC routers to shortcut the 3D contouring process. First and foremost, you want to create your basic shapes and features using 2.5D operations. This is by far the biggest time saver. I’m talking about pocketing, profiling, and drilling mainly flat features on flat parts. You then follow it up with a bit of hand sculpting. This marriage between CNC and hand work produces impressive results for this type of project, while shaving valuable time from the process.

Figure 1. Cutting 2" foam stock

To start, I needed an inexpensive material that I could get from my local home improvement store that was easy to work with. The obvious choice was 2” thick foam insulation which I purchased in a 4 x 8 foot sheet for about $28. It’s thick enough to allow for a lot of depth and contrast in my design, which really pops when hit by a spot light on my lawn display. I happened to pick up a panel of pink Owens Corning — the one with the Pink Panther mascot (Figure 1). Other brands in other colors should work equally well.

I Think I CAM, I Think I CAM ...

My favorite piece of CAM software is Vectric’s VCarve Pro. This is by far the easiest-to-use CAM software on the planet. I also like how their software shows you a 3D preview of what the finished part will look like (Figure 2). I mention the CAM software first because the feature I like best is the built-in drawing tools, as opposed to other applications that require third-party drawing tools. This allows you to blend the first and second phases with a single piece of software.
 

Figure 2. 3D view of the  tombstoned esign in VCarve Pro.

Given that, we will skip the first phase and blend it in to the second phase when we get to that point.

This article is not intended to be a step-by-step tutorial, so I will not go into the details of how to use VCarve Pro. There are plenty of excellent tutorials and sample projects on their website if you need help using any of their software. You can download the design files for this project at the article link or at www.probotix.com/downloads to help get you started or if you want to simply recreate my design.

The first step in the CAM software is to define your stock (length, width, and height) and also where you want the origin (the zero location) to be. You can choose the back right corner at the bottom of the stock, top dead center, front left corner, or the top of the stock — it’s wherever you need it to be. It can depend on a lot of things, but typically people use the front left corner at the top of the stock.

The next step is to import your drawing from another drawing program. In this case, you can take advantage of Vcarve’s built-in drawing tools to create your shapes. I design machines and electronics for a living, so mechanical design comes naturally to me. However, I really struggle with organic design. So, whenever I come across a project like this, I rely on a variety of resources to help me.

Design, Fonts, and Clipart

There are plenty of sources of clipart available online, but many of them are click farms in disguise, so beware. I really like the CD-ROM/DVD clipart collections that include categorized catalogs (long live print!). Most of these designs require a lot of cleanup before they can be machined. They were not designed for CNC and will often have both disconnected and hidden vectors that have to be reworked first. Boolean drawing tools are your friend here.

Another great source of simple shapes are themed dingbat fonts. They require very little work to make them machinable. The horned head in my design was one of the “letters” in such a font. Speaking of fonts, there are tons of free font websites out there where you can find a multitude of themed type styles for your designs.

Once you are satisfied with your design, you will assign tool paths to the various shapes in it. Vcarve has a variety of tool path operations, but for this project we are only using the pocketing and profiling operations. With any of the tool path operations, you will be assigning the tool geometry, starting depth, depth of cut, step-over, feed rate, plunge rate, direction of cut, and so on. Because I was working with foam, I was able to take some overly aggressive cuts.

The order of operations is important when laying out your tool paths. For instance, you may need to cut your shallower pockets first when you have overlapping or embedded pockets. If the stock is being held from the outer edges, the last operation should be to do your final outside profile pass. I didn’t have an end mill long enough to make it through the whole slab of 2” foam, so on my outside profile, I cut it through as far as I could, then hand cut the rest of the way through with a knife. 

Now that you have your tool paths, you export them as g-code through the appropriate post-processor, and then carry that g-code over to the CNC machine on a USB thumb drive and load it into the control software. Our machines at Probotix run the open source software LinuxCNC.

Mount Up

I was cutting this particular part on the Probotix FireBall Comet™ CNC router that has a 25” x 25” work envelope (Figure 3). My foam slab was 18” x 24”, so I had to be careful that I mounted it to the table inside of the travel envelope of the machine. Double-sided 3M tape that has the green argyle backing is what I like to use for mounting stock to my table. Use a generous amount so the stock doesn’t come loose in the middle of the job.

Figure 3. Probotix Fireball Comet CNC Router. Figure 4. Screenshot of LinuxCNC showing tool paths.

Once the stock is mounted, install the tool into the spindle and then jog the tool over to the corner that you chose for the origin in the CAM software. Then, you will “touch off” each axis. What you are doing is telling the control software that you are now sitting at the starting point of each axis, or X0 Y0 Z0.

Give yourself a sanity check and look at the 3D toolpath on the display. You want to make sure that the tool path appears where you think it should within the work envelope bounding box on the screen (Figure 4). Then, hit the start button, sit back, and watch (Figure 5).

About 30 minutes later, you will have the basic tombstone carved out. So, pry it off the table and remove the double-sided tape. Figure 6 shows what it looked like after I cut off the outside scrap. Pretty cool already, but not very scary looking ... yet.

Figure 5. Fireball Comet in action - cutting the tombstone design. Figure 6. Tombstone after maching, but before handwork and paint.

The next step is to hand contour the piece to rough it up so it looks aged and weathered. There are many tools and methods you could use here, and you could spend a lot of time adding detail. Remember how impatient I am, though? I grabbed a die grinder with a rasp bit and a sanding wheel. I also used a hand rasp, and then smoothed out certain parts of the tombstone with some DAP fast drying latex caulk (Figure 7). Watch out for that die grinder — you can remove too much material in a hurry if you are not careful.

Figure 7. Die grinder, hand file, sand disc, and caulk.

Finishing Touches 

So far, so good, but have you ever seen a pink tombstone? Me neither. So, let’s change its color!

I love modern spray paint technology. There are many fast-drying exotic finishes available — your options are limitless. You can get a fantastic finish with little time and effort. A fleck stone spray paint finish was very tempting here, but since most spray paints will dissolve foam, I decided to use latex. I chose a satin gray as my base coat, and then used gray, black, and burnt umber mixes to weather and shade the tombstone (Figure 8).

Figure 8. Painting supplies and brushes.

Save Time, Save Money

You can spend a little time or a lot of time here. These tombstones are typically viewed under low light conditions, so I was looking mostly for contrast and depth, and that didn’t require a lot of time. Here is a breakdown of the time invested in this project:

  • Research: 3 hours
  • Design time: 1 hour
  • CNC routing: 30 minutes
  • Hand contouring: 10 minutes
  • Painting: 30 minutes

So, my total time was 5:10.

Compare that to the 10-20 hours that could easily be spent on a full CNC 3D contouring to accomplish the same thing (Figure 9)!

Figure 9. Finished tombstone decoration.


Ta-Da!

All-in-all, I was pretty satisfied with the results from such a small investment in time. If I were going to do this again, I would have spent more time and creativity on the tombstone verbiage. 

Do a Google search for “funny epitaphs” to get some inspiration. Maybe include names of family members or friends. Add an Arduino and LED lights. Then, make a whole graveyard full of them if you want! 

Most importantly, make sure to work safe and have fun! NV

 

Resources

Probotix Comet CNC Router
www.probotix.com

Royalty Free and Public Domain bitmap and vector clipart libraries
www.openclipart.org
www.pdclipart.org
www.clker.com

Files for this project
www.probotix.com/downloads

LinuxCNC
www.linuxcnc.org

Vectric Vcarve Pro
www.vectric.com

Free Fonts
www.dafont.com

Halloween Fonts
www.dafont.com/theme.php?cat=803

How to draw a creepy tombstone
www.fuelyourillustration.com/draw-acreepy-tombstone-using-adobe-illustrator/

Some definitions sourced from WikiPedia and other online resources


Posted on 10/14 at 2:41 pm
Posted in: Developing Perspectives

The Internet of Things

November 2014 Bryan Bergeron

Since the birth of the Internet, there has been talk of total connectivity — between people, people and their possessions, and things to things. Up until recently, the reality has been that such ecosystems existed only in academic and corporate research centers. Today, the Internet of Things (IoT) is a practical reality in many settings.


Let's start off with consumer goods. For the wellheeled, there's the Philips hue connected bulb ($60). It's a wireless bulb that screws into a regular light bulb socket. The difference is that you can control color and intensity via your iPhone or iPad from across the room or across the globe. If light bulbs aren't your thing (they don't do much for me), then another example of a commercially available IoT device is the Nest Protect smoke and carbon monoxide detector. No more surprises when you return from vacation to find all of your belongings smoldering from a house fire.

Then, there's the Parrot flower pot moisture sensor ($60) so that you know exactly when to water your roses, even when you're away from home. I haven't yet made the move to keyless locks. The Kwikset Kevo wireless deadbolt ($220) — while expensive enough to suggest it isn't a toy — leaves me a bit uncomfortable, knowing that a hacker could unlock my front door from his desk in some other country.

I'm partial to the web-enabled wireless cameras that can be accessed from anywhere. Check who's at the front door, keep an eye on the sitter, make sure the kids are doing their homework — the list is almost endless. Sure, this sort of snooping has been available for years, but never so "plug and play" with a smartphone.

On the non-commercial end of things, I've had the pleasure of working with some expensive gear that has yet to trickle down to the consumer market. My favorite is the pallet tracker. It's an RF unit that not only broadcasts the GPS location of the tagged pallet, but informs the receiver about handling and environmental conditions. 

For example, it can be set to sound an alarm if the internal accelerometer reads over 3 s, or, if the orientation of the tracker is shifted — as in flipped over. With such a device, it's possible to track a shipment across the globe, monitoring not only the location of the pallet but how it's been handled. (Be sure and check out the article this month by Ron Newton on a three-axis hockey puck accelerometer data logger that can be used for just such an application.)

I'm still waiting for a pair of running shoes that tell me not only how far and fast I've run — those have been available for years — but when it's time to buy a new pair of shoes based on impact sensors. It's the same with my toothbrush. I'm never certain exactly when to toss my brush for a new one. A connected brush that sends me an email after, say, 10,000 brushes would be helpful. I expect to see such a brush in my local CVS or Walgreens pharmacy within a year or two.

Best of all, I expect to see IoT kits that allow anyone to put anything on the Internet. Simply glue or nail it on whatever or whomever you want to track or control, and go about your business. One thing's for sure. With a mature IoT, I'll have to upgrade my data plan on my smartphone to avoid overuse charges. NV


Posted on 10/14 at 3:59 pm
Posted in: Nuts and Volts

New and in 3D: Automatic 3D data conversion and 3D-MID prototyping

October 2014

Aarbergen - At this year's Munich Electronica trade fair (November 11th-14th), Beta LAYOUT continues to announce interesting innovations. Brand new for Beta LAYOUT at Electronica is the introduction of “3D-MID prototypes.” Molded Interconnect Device (MID) is the production of moldings with integrated conductive structures. With "Brd - to - 3D,” Beta LAYOUT presents a comprehensive 3D package for its customers. The complete virtual circuit board package can be created directly from an EAGLE *.brd file. Features include photo realistic images of the PCB, SMD stencil, and STEP file generation.


3D-MID prototypes

Brand new for Beta LAYOUT at Electronica is the introduction of “3D-MID prototypes.” Molded Interconnect Device (MID) is the production of moldings with integrated conductive structures. In mass production, these moldings are manufactured using injection molding techniques. For prototyping purposes, this method is not economically feasible. Coming soon, Beta LAYOUT will offer the ability to manufacture MID components in prototype and small batch quantities, including the production of formed components by 3D printing, metallic coating, laser patterning, selective metallization, and mounting.

This technology is economically viable for engineers and companies with prototype and low volume quantity requirements. Start of production is planned for the second quarter of 2015. For design of 3D-MID components, developers can download the free PCB - POOL® edition of layout software TARGET 3001! which will have extended design features.

Brd-to-3D

With "Brd - to - 3D,” Beta LAYOUT presents a comprehensive 3D package for its customers. The complete virtual circuit board package can be created directly from an EAGLE *.brd file. Features include photo realistic images of the PCB, SMD stencil, and STEP file generation. In addition, a freely rotatable 3D view in PDF format is created which can be viewed using Adobe Reader. A link to order a laser sintered 3D model of the assembled PCB is provided, and a free 3D model is offered with PCB-POOL® prototype orders that can be used effectively for collision checking.

In addition, visitors to the Beta LAYOUT booth can receive information on the entire product range and services provided by Beta LAYOUT. These include PCB-POOL® - PCB prototype manufacture, PCB assembly, LASER STENCIL - SMD stencils, BETA – PROTOTYPES - 3D rapid prototyping, PANEL-POOL custom front plate manufacturing including color printing, and the BETA-eSTORE - tools and aids for prototype PCB assembly. www.beta-layout.com


Posted on 10/14 at 9:41 am
Posted in: Nuts and Volts

WiDo - Open Source IoT Node (Arduino Compatible)

October 2014

The WiDo Open Source IoT Node Arduino Compatible is a WIFI IoT Node development board, which integrates WG1300 WIFI solution. The Wido's microcontroller is ATMEL ATmega32U4 and is maker friendly. Fully compatible with Arduino and periphery modules. This is a credit card sized controller that comes with everything you need to connect to the cloud. And it's under $30! 


  • Arduino compatible WIFI IoT Node development board
  • Integrates WG1300 WIFI chip
  • Support 2.4GHz IEEE 802.11 b/g network
  • On board 2.4G PCB Antenna

 

Get yours today at the Robotshop.com


Posted on 10/14 at 9:14 am
Posted in: Nuts and Volts

Kickstarter: Dr.Duino

September 2014

Arduino has taken developers by storm, making developing your next widget easier than ever. But testing and debugging your next big thing is difficult and pains taking with Arduino. Stacked boards prevent access to the ones underneath it. Forcing you to stack and unstack your megalithic tower countless times each time bending pins out of shape, possibly breaking them. OUCH! What’s more, attaching probes for monitoring purposes is a pain, and what about a ground pin for my Oscilloscope, Digital Multi-meter (DMM) or Logic Analyzer?


Test Points, Test Points, Test Points!

Never struggle with where to grab a ground or monitor any signal from your Arduino to the shield above it again.

  • 4 large Gnd test points!!
  • 4 extra-large 5V &3 V test points.

Each test point is color coded for easy recognition.

  1. Green = Ground
  2. Red = 5 Volts
  3. Orange = 3.3Volts
  4. Black for Vref, Vin, and extra I/O!

RS-232 Baby!

Yep, built in RS-232 support out of box!

Communications Loop back testing supported by a simple jumper.

Built in Siren

Is your Arduino too far out of reach but need to know if an output is high or low? Well, assign your output pin to this little guy and BAM just listen for the siren! Better yet, this is connected directly to one of the PWM pins allowing you to control the volume.

Switch It UP

4 push button switches tied to input pins.

2 active high and 2 active low.

Light It UP

4 LED’s to help you debug your code.

Connected to the Arduino’s PWM pins allowing you to control brightness too!


POTs, POTs and more POTS

Six 10K large thumb wheel rotary Potentiometers pumped directly into the analog input pins.

Reset Switch

Reset your stack via the readily accessible reset switch.

How about some headers Please?

Every pin of the Arduino board has been brought out to a header. Allowing easy access for debugging purposes.

The window to your Boards Soul-

The middle of the Dr.Duino™has a hole! That’s right, simply plug your testy shield into any level of your stack. This allows you to still have access to all of your previous shields pins, IC’s, wires etc.

Pseudo Hardware

Were you struck in the middle of the night by your next invention but don’t have hardware on hand? Well, use the Dr.Duino™ kit and start writing your application code within mere milliseconds via commonly used hardware. Switches, POTS, LED’s, Sirens. Just plug in your Dr.Duino™ into your Arduino and start writing code!

 

Visit Dr. Duino Website to learn more! Or check out the Kickstarter to back the project! 


Posted on 09/14 at 2:57 pm
Posted in: Featured Article

The Ghost Phone

October 2014 Anthony Petrone

You walk into a darkened room where a rickety antique desk holds a dusty old telephone. To your surprise, it rings! You pick up the handset and hear static, hissing, and — just below the surface — the whispery words and scary sounds of a ghostly presence! You've just answered the Ghost Phone!


Figure 1A: Candlestick Style Phone

Since the days of old, many people believed the veil between the land of the living and the domain of the dead is at its thinnest on Samhain, All Hallows Eve, or — as we know it today — Halloween! Soothsayers, shaman, psychics, and mediums would all claim to provide patrons the privilege of speaking to their long-lost loved ones or would offer to carry back messages from the other realm — for a nominal fee, of course. So, how about we just skip the middleman and create a direct line to the afterlife? If this sounds like fun to you, then this fairly simple Halloween prop is just the ticket!

Propping It Up

I set out to create the Ghost Phone as a fun and interactive prop that anyone could make, using found objects and/or parts bought from local stores. Once the basic parts are gathered, it is unlikely that you'll spend more than a couple hours getting it all up and running since there's just a little wire splicing required. No tricky programming or custom-crafted printed circuit boards (PCBs) will be needed here. The premise is simple enough: When people get near the phone, it rings suddenly! Those brave enough to answer will be greeted with ghostly voices from the beyond.

There are three main components to this project; first of which is the phone itself. A suitable candidate can typically be found in a dusty corner of a thrift shop, in a box of junk at a garage sale, or maybe hidden in your very own attic. Second is the audio system which consists of a snap-action microswitch and a small MP3 player with a cheap set of headphones or earbuds. The third and final part is the ringer system. Though it may be possible to use the existing bells in the phone, I found it simpler to purchase an inexpensive low voltage electric bell and a "doorbell" style transformer to drive it. To control the ringer, I went to my local hardware store and purchased an off-the-shelf wireless light switching system that came with a handheld remote.

Though you can use pretty much any old corded phone for this project, I suggest you go for a style that fits the era of the haunted room in which you intend to use it. Victorian, Candlestick, WWII Army surplus, or even ‘50s era big black Bakelite style phones are all good candidates. Keep in mind that the modifications will likely render the phone unusable for "normal" phone service, so make sure you're not inadvertently destroying an expensive antique or family heirloom! For my haunt environment (classic Victorian haunt atmosphere), l found and purchased a replica Victorian-style phone.

Figure_1B: 50's Era Big Black Bakelite Style Phone Figure 2: Victorian Style Phone

Sounds ... Scary!

In operation, you want to give your guests the illusion that they are hearing voices from beyond the grave, but only when they pick up the receiver. To do this, I had to discover which wires went to the speaker in the earpiece of the phone handset. A quick search around Google and Wikipedia shows that many handsets used four wires: two for the microphone and two for the earpiece speaker.

Figure 3: Microphone to Speaker Wiring Schematic

We will need to access the two wires that go to the speaker in the handset. Lucky for us, older model telephones were long-lived devices and are typically easy to open for repairs. As such, it's normally a simple matter to unscrew the cover from the phone base and reveal the internal terminals and wiring. Once you have the cover removed, look carefully for the wires that come from the handset.

If you're lucky, they may be coded with the standard black/red/green/yellow colors. If this is so, you can try using the battery "tap test" to see if you can quickly identify the speaker. To do this, hold the green wire on the bottom terminal of the AA battery, then "tap" the red wire on the top terminal. At each tap, you should hear a pop and/or a slight crackle sound come from the speaker. If this doesn't make a sound on your first round, you can try each set of wires in turn until you hear the sound come from the ear piece.

If you prefer not to "experiment" looking for the speaker wires, you may disassemble the handset and check to see which two wires are connected to the earpiece. Many older phones feature a circular style ear and mouth piece on the handset that may simply be unscrewed. Some newer models may require you to pry the handset apart to gain access to the speaker.

Figure 4: Disassembled handset to find the speaker wire in the ear piece.

In any case, exercise caution not to break anything and make sure you can put it back together again. After you have identified which wires go to the earpiece in the handset, the next step is to modify the base.

Switch It Up

Once the speaker wires are located, we are going to wire in our MP3 player. We need an 1/8" stereo plug that ends in bare wires. If you have an old pair of ear buds or if your MP3 player came with a pair you are willing to sacrifice, simply cut the buds off the ends to create the cable we need. Carefully strip the wires from one side of the headphone cables (either the left or right speaker). Once you have stripped the wires, we are going to splice them into the handset speaker wires and our microswitch.

Figure 5: Wiring in the MP3 Player to the Phone.

In order to use the microswitch, we are going to find the "hook mechanism;" this is the piece that goes up and down when the handset is picked up. Depending on the type of phone you have chosen for this project, the next step might take some creativity. You will want to attach the microswitch to the moving piece of the hook mechanism so that when the phone is "on hook" (the handset is down), the connection to the speaker is open; when it's picked up ("off hook"), the connection is completed. I positioned my microswitch in such a way that the hook mechanism would push against it when the handset was down.

We want to wire one of the leads from our headset to the normally-closed position so that when the switch is released, the circuit is completed and the audio is allowed to play. Essentially, you will be breaking one side of the speaker connection with the microswitch.

You may need to remove most of the phone's internals to do this. That's okay, since we will want room inside to mount the MP3 player as well.

If you have followed these steps correctly, you should now be able to put a spooky MP3 of your choice onto the MP3 player and test out your work for the first part of this prop. Be sure to set your MP3 player to loop endlessly. Pick up the handset and make sure you can hear the player coming through the speaker.

If for any reason you cannot, be sure to check your wiring. These wires can often be very small and difficult to work with, so take your time and double-check your work. Be sure everything is working as it should, then reassemble the phone. If you picked a sufficiently small MP3 player, you should be able to hide it inside the phone itself. 

Figure 6: MP3 Player hidden in phone base.

There are plenty of great free spooky MP3 sounds you can download on the Internet, or you can make your own if you know how. Since we are using only one speaker, be sure to make your audio track of choice mono.

The second part of the prop allows the phone to ring when guests are near it and is much easier to make. To give the illusion of the phone's omnipresent sense for ringing, we are going to use an old-fashioned doorbell with a 2.5 inch bell and connect it to a wireless light outlet. The host can secretly hide the transmitter in their pocket or hand and control when the phone rings. These doorbells and the doorbell transformer can be found at most local hardware stores and online.

In order to hook the doorbell up to the wireless light outlet, we are going to use an old power cord for a PC and the doorbell transformer. The transformer will take the 120 VAC from the wireless light outlet and drop it down to a more usable 12-16 VAC for the doorbell itself.
 

Figure 7: The Doorbell Transformer hooked up to the Wireless Remote

Trim off the female end of the power cable and strip the wires back. Next, splice the end of the cable to the 120V side of the doorbell transformer and then wire the doorbell to the other side. Now, we can plug the cable into the outlet on the wireless transmitter, giving us a wireless ringer for the phone. You will need to turn the bell on and off by hand, so try to do so in a way that makes it sound like a phone ringing and not simply an endless ring.

Once the ringer is complete and tested, you can now hide it on the bottom of the table or desk that you are placing the phone on. Most tables and desks have a recessed area on the bottom which is perfect for hiding the mechanism. Practice a few times with the ringer to make sure you get the hang of making it sound like a phone, and be sure to stop once a guest picks up the handset! This prop is great because it has a nice startling effect of the loud bell ringing when people least expect it, and it's even creepier when guests realize they can answer the phone and hear the spooky voices from the other side.

This project was designed so that anyone could build it with simple-to-find parts, regardless of their skill level. A more advanced approach could be done using something such as an Arduino kit with an MP3 player board and PIR sensor to help automate the prop. You can find videos of the ghost phone in action at http://youtu.be/qx_Mujj_wbA.

For more fun Halloween project tips and ideas, be sure to check out my site at www.EerieAcresCemetery.comNV

 

 


Posted on 09/14 at 9:37 am
Posted in: Developing Perspectives

Don’t Get Stung by a Wall Wart

October 2014 Bryan Bergeron

Wall warts are used in place of internal AC-to-DC power supplies in most small devices — and for good reason. The powered unit can be more compact because of the obviously smaller parts count. There’s also no need to make allowances for convection cooling of components in the powered unit. The downside, of course, is the need to control a neverending, space-hungry herd of wall warts.


Until recently, a typical wall wart in my collection required at least two outlet spaces in my power strips: one for the prongs of the wall wart and at least one adjacent outlet partially obscured by the body of the wart. Given that new compact switching wall warts are so inexpensive, I recently upgraded my collection of conventional transformer and diode bridge warts to the switching variety. I’ve been happy with the upgrade — there’s more space in the outlets and less clutter around my workbench.

Unfortunately, I learned the hard way that the latest generation of “regulated output” switching wall warts can have at least one major shortcoming: the regulated output can be up to 100% over the stated output voltage with no load. For example, a 9 VDC wart can output up to 18 VDC with no load. This isn’t universal, but depends on the design of the switching supply.

I discovered this when I shipped out a dozen Arduino based animatronic systems for a research project. The systems left my shop — fully burned in — without a problem. However, the systems (which used 9 VDC switching wall warts for power) were DOA. I first thought of ESD, and modified the front end circuits of the animatronic systems to bleed off any electrostatic charges.

Luckily, before I sent the second batch of units off to the field, I ran across a thread in a forum about the no-load voltage levels in the same switching power supply warts I was using. It turned out that the users of my systems were plugging in the warts first, and then connecting the animatronic systems. This was guaranteed to generate a chipkilling spike if the no-load voltage was significantly greater than the load voltage. I solved the problem by ordering a dozen of the old-fashioned bulky wall warts with conventional non-switching circuitry. Problem solved — after quite a bit of expense repairing and reshipping the animatronic units.

Of course, not all switching wall warts suffer from this no-load voltage problem. The wall warts weren’t something I found on eBay. They were standard items from my favorite parts supplier. Bottom line: Verify that the wall wart’s output is what you expect before plugging it into that new system you’re designing. NV


Posted on 09/14 at 9:08 am
Posted in: Featured Article

Rubys Flame Extended Article

September 2014

A friend of ours, Ruby Joule, who is a dancer in the world famous Jigglewatts Burlesque Troupe from Austin, TX asked if we could help her with a prop she wanted for her stage act. She had been wanting to do something involving fire, but most venues tend to frown upon using real flames. She had seen photos of some of the Halloween props we had built, and asked us if we’d be interested in fabricating something for her.


She wanted us to create a four foot tall faux flame prop.  It needed to be easy to carry on and off stage by anyone immediately after her performance was completed. This was important as the stage has to be clear for the next act. This also meant it needed to stay cool all the time (no halogens) and be rugged as it would be subject to road life abuse and the occasional clumsy stagehand. We went through a few different designs, but eventually made the stage prop now known as "Ruby’s Flame."
 
We’ve had a lot of requests from others who have wanted to build this for their home haunts, and recently by a few drama teachers who wanted to use it in some school performances. One of them told us it was the hit of their play. Thanks for the inspiration, Ruby! 
 
Build the MDF Enclosure

Let’s get started by building the enclosure. Figure 1 shows the parts that will be necessary to complete this. Measurements to build the cabinet itself and the luan top with all the cut information are as follows:

2 — Long side panels cut to 23-1/2” L x 9-3/4” H
2 — Short panels cut to 7-1/8” W x 9-3/4” H
2 — Inside runners for suspending the luan top cut to 22 -1/8” L x 1” W, shelf for PC power supply cut to 6-3/4” W x 7-1/4” L, Luan top cut to 22-1/4” L x 7-1/8 “ W

NOTE: See the section on installing the legs and leg nuts before continuing — it’s a good idea to install the T-nuts that are needed to attach the legs before you assemble the enclosure!

Figure 1. The parts. Figure 2. The raw enclosure.
Figure 3. Side rails measured. Figure 4. Bottom shelf view. Figure 5. Bottom shelf with side rails installed.

Make the enclosure box by assembling the two long side panels and the two short panels to form a rectangle. The short panels fit inside the long side panels to form this box. Dimensions of the final box will be 23-1/2” L x 8-1/2” W x 9-3/4” H (Figure 2). Use wood glue and secure with wood screws.

Measure 1-1/2” down from the top, inside the enclosure, and attach a runner to each side. This is what will support the luan top panel. Use wood glue and secure with screws (Figure 3).

Figure 6. Top panel/full view
 
Figure 7. Half of top panel with measurements for the layout.


Turn the box over so its bottom is facing upright. Measure down 1” and over 3” from the side, then attach the shelf for the power supply so it sits about 1” from the bottom (Figures 4 and 5).

The Top Panel

This is the most important step to the whole project! The panel needs to fit snugly and be measured correctly as it will support the fans, the lighting, and the silk flame itself.

Measure to the center of the luan top and draw a line widthwise to divide the top (dividing line), then draw a second line lengthwise to divide the top again (center line). This will leave you with four sections to measure from. All of your measurements will start there, so make sure that everything is centered (Figure 6).

Each side will need to have one 5” hole and two 1-5/8” holes.

Figure 8. These marks show where to drill for the LEDs.

 
Figure 9. These marks show where to drill for the LEDs.

 
Figure 10. These marks show where to drill for the LEDs.


For the 5” hole, measure from the dividing line along the center line and make a mark at 3-3/4”. This will be the center of the 5” hole for each fan. Repeat this for the other side (Figure 7).

For the two 1-5/8” holes, measure 1- 3/8” from the edge of the top along the dividing line and make a mark. From this mark, you will measure 7-5/8” across the length of the luan top to mark the center of the 1-5/8” hole. The finished hole should be 1/2” from the length side and 2-5/8” from the width side. Repeat this for the remaining three holes. You will also need to drill out two holes for the 10 mm blue LEDs to mount into. We put one LED on each side of the center line and along the dividing line. You will want to drill a hole as in Figures 8, 9, and 10.

Helpful Tip: 
Take a scrap piece of luan and drill a hole approximately the same size as the 10 mm LED. You want the hole just big enough so the LED will fit snuggly without gluing it. This way, you will know what size drillbit to use to make the actual hole in the panel. We ended up using a step bit to get the exact size we needed, but I don’t recall what size it was. Using the scrap wood will allow you to figure out what the final hole size needs to be so you can be sure to drill the right size in the actual panel.

Building the Light Harnesses

We’ll begin with the light harnesses utilized. Start by taking about one foot of black wire and soldering it to one of the wires from a GU10 socket. It doesn’t matter which wire you use (Figure 11).

Figure 11. Solder the black wire to the GU10 socket. Figure 12. Solder the white wire to the GU10 socket. Figure 13. Shrink wrappng the wires.


Next, take about one foot of white wire and solder it to the other wire on the same GU10 socket and cover these solder joints with shrink wrap (Figures 12 and 13). You will now need to cut a second piece of black wire approximately one foot long. Solder the two black wires together with one of the wires from a second GU10 socket (Figure 14). Now, do the same thing with a piece of white wire. Cut a second piece approximately one foot long. Take the GU10 socket and solder these wires together with the remaining wire from the second GU10 socket (Figure 15). Shrink wrap both of these solder joints. This will complete the first of two wiring harnesses you will need to make for the GU10 LED lights. Figure 16 shows a shot of the completed wire harness.

Figure 14. Solder the second black wire to the second GU10 socket.  Figure 15. Solder the second white wire to the second GU10 socket. Figure 16. A completed lighting harness.
 


You will need two wiring harnesses, so repeat the steps above and set them aside for now.

Making the LED SpotLight Holders

To make the spotlight holders (Figure 17), you will need to use a step drill bit (Figure 18) and enlarge the hole in a shallow flange so the opening is the same size as the lens on the bulb (Figure 19). The easiest way we found to do this is to take a short piece of 1-1/2” PVC and place the flange on top; it will slip over the end of the pipe. Then, drill out the hole with the step bit. The lens on my LED spotlight is about 1-1/4”. If you have a drill press, it will make this easier, but it can be done with a handheld drill if you are careful (Figure 20).

Figure 17. LED spotlights in action. Figure 18. Step drill bit. Figure 19. The shallow flanges before and after expanding the size of the hole. 


Repeat this for all four of the necessary flanges, then set them aside for now. We ended up painting all of the parts black so they would disappear when the flame is on. This is a good time to paint parts if you choose to do so (Figure 21).

Figure 20. Enlarging the hole in the shallow flange with a step bit. Figure 21. We painted all the parts and hardware black.
 
Figure 22. Connecting the GU10 bulb to the GU10 socket.
 


The GU10 LED lightbulbs fit perfectly inside of 1-1/2” PVC/22-1/2 degree angled Els. They are also the perfect angle to shine onto the silk flame. The GU10 socket will come up from below the top panel of the enclosure, through the PVC EL. When the LED is attached, the bulb will sit perfectly inside the angled El (Figure 22). You can then cut a small disc of lighting gel and place it on the bulb to take intense heat away. However, these LEDs barely get warm. Next, take the coupling flange you drilled out earlier and snap it onto the flange to secure the gel and bulb in place (Figure 23).

Figure 23. Attaching the shallow flange to the PVC light holders. Figure 24. Drilling the fan holes with a 5" hole saw. Figure 25. We used 1/2" Tek lath screws to attach each fan to the bottom of the top panel.  Figure 26. Laying a bead of clear silicone caulking around the base of each fan.


Installing the Fans

The flange itself will lock onto the PVC El, so no glue or fasteners are needed. Besides, you might want to alter the color of the flame at some point. We will eventually position the Els and then glue the base to the top panel of the enclosure, but we’ll do that later once the silk that creates the flames is actually flying. The assembly of the spotlights will be part of the final assembly and wiring.

The particular fans we use are very dangerous when spinning and could probably take off a finger, so always use extreme caution!

The fan’s casing is square and the holes we drilled are round, so we used all-purpose silicone caulking to help plug up around the fans and also to assist holding them securely to the top panel. We’ll use four 1/2” lath screws per fan to secure them, as well.

Figure 27. Both fans mounted to the top panel of our enclosure with screws and clear silicone caulking.  Figure 28. Flipping over the top panel so we could smooth out the caulking.
 


Start by drilling some very small holes into the luan in each corner, lining up with the holes in the corner of the fan (Figure 24). You will need to position the fan so that you can put a screw into each corner to secure it to the top panel (Figure 25). Make sure each corner lines up with the holes in the corner of the fan so you can put a screw into each hole to secure it. You will also want to make sure that the fans are facing the correct direction so when they spin, the air flow will be blowing where it’s supposed to. Usually, the label side is what you want to see when it is mounted to the top and flipped back over to the operating position.

Figure 29. Smoothing out the caulking using some rubbing alcohol. Figure 30. Wiring up the 10mm blue LEDs.
 
Figure 31. We drilled a small hole in the base of the power supply to attach it to the shelf.

Make sure to fill in any open spaces around the hole so you don’t lose any air flow (Figures 26 and 27). You can run a thick bead of the silicone caulking around the fan to help seal it. Once this is done, flip the panel over and smooth out the silicone (Figures 28 and 29). Set the piece aside to dry overnight.

Helpful Hint:
Greg showed me a little trick he learned from a tile installer. To smooth out the silicone caulking, put on a nitrate glove and dip a finger into some rubbing alcohol. Then, run your finger over the silicone. The silicone won’t stick to the glove due to the rubbing alcohol.

 

Continue to Rubys Flame Extended Online Version - Part 2  ..


Posted on 09/14 at 10:31 am
Posted in: Nuts and Volts

What’s in the box?!

September 2014

Monster in a Box! Just one of the many Halloween projects found in the September 2014 Halloween Spectacular issue of Nuts & Volts. Just imagine that there is a Fire breathing monster inside trying to escape! Activated by motion sensors, all you'll need to do is get the unexpect tricker treaters near the box for it to start shaking with the fog machine and mp3 player inside, you'll be sure to get a nice scare out of the kids this year. Read more to watch a video of the Monster in a Box! 



Posted on 08/14 at 11:17 am
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